Over the last few decades there has been developing interest in non-traditional treatments for certain types of cancer. Recombinant toxins, hybrid proteins composed of a bacterial toxin and either a growth factor or a portion of a recombinant monoclonal antibody, have received significant attention in cancer therapeutics.
Human DNase I has been used as a therapeutic agent for the treatment of wounds and ulcers, bronchitis, inflammatory conditions, herpes infection and most notably, cystic fibrosis. The cytolethal distending toxin (Cdt) is a genotoxin, produced by several species of bacteria including the periodontal pathogen Actinobacillus actinomycetemcomitans. 
Cytolethal distending toxin (Cdt) is a family of secreted bacterial protein holotoxins that classically arrest the growth of specific types of eukaryotic cells or cell lines at either the G0/G1 or G2/M phase of the cell cycle. The holotoxin is the product of three genes expressed by a handful of facultative or microaerophilic gram-negative pathogenic bacterial species. The species identified to date that express a biologically active CDT include select strains of enteropathogenic Escherichia coli, Campylobacter jejuni, Campylobacter upsaliensis, Campylobacter coli, Shigella dysenteriae, Haemophilus ducreyi, Helicobacter hepaticus, Helicobacter flexispira, Helicobacter bilis, Helicobacter canis and, the periodontal pathogen, Actinobacillus actinomycetemcomitans. Organization of the genetic locus as well as the structure and biological activity of the holotoxin are fairly well conserved among the bacterial genera that express the Cdt. Biologically active toxin is a heterotrimer composed of approximately 18-25 kDa (CdtA), 31 kDa (CdtB) and 21 kDa (CdtC) protein subunits expressed from a polycistronic operon. An adjunct property of the cdt genes is that they appear to have a eukaryotic rather than prokaryotic heritage. The cdt gene products exhibit deduced amino acid sequence and structure/function similarities (albeit weak) to those of eukaryotic proteins.